Aquarium volume calculator

The arithmetic works inside the glass, not on the box: wall thickness comes off each pair of walls and the bottom, substrate displaces its footprint times its depth (treated as solid, so a porous bed holds a little less), and the rim gap drops the water line. The bow front models the bulge as a half ellipse across the front, and the hexagon works from the flat-to-flat width, which is why a side length enters multiplied by the square root of three. Gallons are the exact definitions, 3.785411784 litres to the US gallon and 4.54609 to the imperial one. Weight uses 1.0 kg per litre for fresh water and 1.025 for average seawater, so treat the figure as what the stand carries with a small margin on top; it does not include glass, stand, filter, or livestock.